1. Field of the invention
The present invention relates to anchoring into concrete. More specifically, the present invention relates to a pilot holes mold that when placed on the concrete forms and as concrete is poured and sets, pilot holes are impressed in it.
2. Prior art
At the present time anchoring into precast concrete or other profabricated concrete components, is generally done with powder actuated fasteners and by drilling in the concrete to install anchors.
Powder actuated fasteners often break the surface of these high strength concrete structures and drilling into them is extremely difficult.
Considering the number of building members and parts requiring connection to a concrete structure such as; wood framing, wood trusses, clips and hangers for plumbing pipes, duct systems, electrical conduits equipment, suspension systems for ceiling components, electric fixtures and many others, one can Judge the amount of work and expense involved with the use of powder actuated fasteners or by anchoring into drilled holes.
These time consuming methods require the use of very expensive special tools which are often lost in the job, plus costly powder loads and masonry drill bits.
Another method commonly used to anchor wood members to poured in place concrete structures is embedding metal connectors as the concrete is poured and leveled off.
Embedded connectors will then anchor wood frame walls to poured in place concrete structures such as; footings, monolithic footing-slabs, bond beams, walls, where each wood member must be connected.
Installation of floor or roof trusses over masonry walls, requires connection of each truss to the embedded connectors in the bond beams.
Anticipated placing of embedded connectors must carefully follow the spacing of the wood members in the architectural and engineer plans as these wood members must fall vertically and directly over the embedded connectors.
Skilled help is required with knowledge of construction practices, codes regulations and plan reading to provide the layout marks on the form boards for anticipating the location of embedded connectors.
As concrete is poured connectors are embedded at their anticipated locations marked on the concrete forms, once it sets, construction proceeds with the erection of wood members.
Simpson Strong-Tie catalog C-89H-1, page 36, Models ETA, ETAT are examples of wood to concrete connectors. Palm Beach County Illustrated Code provides an example of wood to concrete connector requirements.
At this time is found that a vast majority of the wood members do not coincide with the connectors previously embedded in the concrete structure. A very common problem with a costly solution.
New connectors must be fixed to the concrete with powder actuated fasteners. A minimum of 4 11/4 inch long steel fasteners per connector must be used, Example; Low velocity fastening systems, Ramset, File LOVEL 18A May 24, 1985.
When many connectors, usually more than three connectors in a building, are added or replaced with powder actuated fasteners, its installation must be inspected and certified by a professional engineer.
This procedure proves costly: Loss of material and labor for misplaced embedded connectors; the need for skilled help; labor and materials to install replacement connectors; expensive powder actuated fasteners; plus required engineer certification for repairs.
Anchoring methods presently used have metal upstanding and protruding over or out from the forms or extending upward in bond beams, walls, slabs, which interfere with the finishing of the concrete surfaces, and create hazardous obstacles to workers erecting the wood structural members around them.
When a wood sill plate is used to connect wood members to concrete, the sill must first be attached to the top of the foundation, slab, wall or beam. There are several ways to attach a wood sill plate to the top of a concrete structure.
The oldest way is to insert threaded anchor bolts into the concrete as soon as the pour is completed and leveled off. Holes are drilled in the wood sill plate and is then set on the foundation with the anchor bolts protruding through the holes and fixed in place with washers and nuts.
Several manufacturers are offering sheet metal connectors which replace the threaded bolts in wood sill plates. An example of a sheet metal anchor is found in U.S. Pat. No. 4,404,781.
Wood members erected over a wood sill will then require additional wood to wood connectors, such as the Hurricane Tie RT-12 manufactured by United Steel illustrated in the Kant-Sag 1987 Catalog page 22. It takes 2 RT-12 clips and 12-8d or 16-6d galvanized nails to connect each member to the wood sill plate.
The wood sill method translates into a great labor and material consuming task and often damage wood members caused by the excesive nailing required for wood to wood connectors.
Another method presently in use to anchor connectors in concrete is the Tapcon concrete fastening system. It requires a hammer drill and a special Condrive tool to drill into the concrete and to drive the anchor in the drilled hole.
The hole is drilled 1/4 inch longer than the anchor then the dust is removed with the aid of a blow out bulb or compressed air, and using the Condrive tool the Tapcon threaded anchor is installed, These products are covered under U.S. Pat. Nos. 3,937,119 and 3,965,510.
Previously mentioned methods are time consuming, some require additional wood to wood connectors, others require expensive special tools.
Anticipated location for embedding connectors in concrete must be done by skilled help and create hazardous conditions for workers.
Replacing misplaced embedded connectors with powder actuated fasteners must be certified by a professional engineer.
In view of these and other prior art deficiencies, it is accordingly the primary objective of the present invention to provide a new and novel article of molding to make pilot hole impressions in concrete means for anchoring connectors in concrete structures.